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Data representation

Selecting the type of representation (or graph) depends on the type of data.

  • The most common forms of representation for categorical (or categorised) data are the bar chart or pie graph.
  • For numerical data, the number of data values will affect the selection.
  • The most appropriate form of representation for smaller numerical data sets is likely to be the stacked dot plot or the stem-and-leaf plot. These are adaptable for comparing two data sets.
  • Histograms are a useful graphical form for large numerical data sets. Box plots, which show a summary of the data in five values, are also useful for large data sets.

Other representations should also be considered. A scatter plot is appropriate for showing an association between two variables measured on the same cases.

Linking graphs to data types

The type of data collected will influence the possible graphical representations that can be sensibly used.

Creating pie graphs

Although pie graphs are not explicitly mentioned in the Australian Curriculum: Mathematics, they are encountered every day in the media and other subject areas. Hence they are a relevant topic for good teaching.